Amortised Cost vs. Fair ValueMedium

The same bond, bought on the same day, reported three different ways. The choice was made before anybody knew which way the market would go, and it decides whether a loss appears at all.

5 min read · 813 words

One holding, three answers

• Amortised cost. Carried at what was paid, adjusted towards what will be repaid, interest recognised evenly. Market prices are not used at all: a price move produces no accounting entry.
• Fair value through profit or loss. Remarked every reporting date, and every movement runs straight through reported profit.
• Fair value through other comprehensive income. Remarked, but the movement is parked in a reserve inside equity. Profit stays smooth; equity moves; the loss is disclosed where a reader has to go looking.
• Nothing about the bond differs between the three. The number differs. How a position hits the books is the mechanism in full; this is the comparison.

What decides which one applies

• Not the instrument's name. Two banks can hold the identical bond and report it differently without either being wrong, which surprises people and is the whole design.
• The business model — what the holder is actually doing with the asset. Holding to collect the contractual payments points one way; holding to sell points another; doing both points at the third.
• And the cash-flow shape — whether the contract pays only principal and interest. Anything with an embedded derivative fails that test and lands at fair value through profit whether or not anybody wanted it there.
• The choice is made at recognition and rarely revisited, which is why it is invisible from outside: it was decided before the outcome that made it matter.

The trade-off, stated fairly

• The case for fair value: it is what the asset is worth. A holder carrying something at a price the market stopped agreeing with years ago is publishing a number that has quietly stopped meaning anything.
• The case for amortised cost: for an asset held to maturity, the interim price is noise. Running it through profit makes reported earnings swing with a market the business has no intention of selling into, which describes volatility rather than performance.
• Both are true, and the framework is the compromise — measure by what the holder is doing rather than by a single rule. That is defensible and it has one consequence nobody can remove: the same economic position can be reported three ways, so a reader who does not know which rule is in force cannot interpret the number.

Where the difference goes when it is not in profit

• Under amortised cost the fair value is still disclosed — in a note, without a headline, in the back of the report. Reading that note is the whole skill, and reading an annual report says where it sits.
• Under fair value through equity the movement is in the reserve, so it is visible in the equity statement and absent from the profit line every commentary quotes.
• Both become profit the moment the holding is sold. The whole accumulated difference arrives in one line, in one quarter, for a move that happened over years.
• Which is why a forced seller is a different animal from a holder. The intention that justified amortised cost was "we will hold this", and a depositor run removes the choice. That sequence — not a credit loss, not a fraud — is March 2023.

The comparison

What to do with this as a reader

• Find out which rule produced the number before interpreting it. This one habit does more work than any ratio.
• Compare the amortised-cost carrying value with the fair value in the note, and read the difference against equity rather than against the portfolio. That is one subtraction and it is the arithmetic behind the most-discussed bank failure of recent years.
• Ask what would force a sale. An unrealised difference is only theoretical while the holder keeps the choice, and the question is never "how big is it" alone — it is "how big is it, and who can take the choice away".
• And separate the measurement from the economics. Reported profit and economic outcome are two different questions, and knowing which one a number answers is most of financial statement analysis.